It is known to supply a sulfuric acid/hydrogen peroxide mixture (SPM) to a front surface of a substrate to remove a resist from the front surface of the substrate.
When a high-dose ion implantation has been performed on a wafer, a hardened layer may format a surface of a resist due to hardening of a surface layer of the resist by carbonization and alteration of the resist.
Patent Document 1 proposes a method for removing a resist from a front surface of a substrate without performing asking even with a resist having a hardened layer at its surface. This document discloses a method for supplying high-temperature SPM to remove the resist, a surface layer of which has been hardened due to ion implantation, from the substrate.